The invention relates generally to cavity wall function and, more particularly, to mapping of center point trajectory movement of the cavity.
The assessment of ventricular wall motion is important in patients with suspected or known cardiac disease since it provides quantitative assessment of cardiac function. Ventricular wall motion evaluation is used for clinical decision-making regarding the need for more aggressive medical and/or interventional therapy such as cardiac resynchronization therapy. The non-invasive evaluation of ventricular wall motion is typically performed during rest, exercise, or while under pharmacologic stress and may be based on an imaging modality such as echocardiography, radionuclide imaging, magnetic resonance imaging (MRI), or computed tomography (CT).
Traditional assessments of wall motion during rest or stress include global parameters of left ventricular volumes and ventricular ejection fraction (EF), which is derived from ventricular volume determinations. However, it is not uncommon for patients with mild forms of cardiac disease (e.g., small myocardial infarction) to exhibit only regional wall motion abnormalities while preserving their global parameters (i.e., normal ejection fraction). Detection and quantification of regional wall motion changes are important for early disease detection, surveillance of disease progression, and/or assessment of therapeutic outcome. Regional wall motion analysis is also important for provocative cardiac function testing such as dobutamine stress testing for myocardial viability.
Regional wall motion assessment can be performed visually, but inter- and intra-observer agreement is often less than optimal and highly dependent on reader expertise and experience. More quantitative assessment of regional wall motion can be determined using computer assisted measurement of regional ejection fraction, whereby regional sub-volume ejection fractions are determined, or by measurement of segmental wall thickening. Specific imaging techniques that directly measure the movement of the myocardial wall such as tissue Doppler using echocardiography and specialized MRI pulse sequences (e.g., DENSE or myocardial tagging) are known. These echocardiographic and MR imaging techniques, however, use additional time to acquire specialized data sets and for operator-initiated image post-processing. Some of these quantitative methods can track changes over time and can be used to determine intra- or inter-ventricular mechanical dyssynchrony. Despite the large number of available methods, however, visual assessment (i.e., a qualitative method) of wall motion is still the most widely used, but its application is heavily reliant on observer experience and expertise. Quantitative methods such as those described above are associated with a variety of limitations including prolonged image acquisition times, high observer interactive time and expertise requirements, inherently high spatial and/or temporal resolution requirements, and/or high imaging data/processing requirements.
It would therefore be desirable to have an apparatus and method capable of quantitatively assessing cavity wall motion efficiently while reducing variations in observer-based assessments.